Recruitment for this demanding longitudinal study is in its early stages due in part to the successful development of imaging techniques required to measure gonadal volume in these children with Magnetic Resonance Imaging (MRI), the need for a designated functional MRI to be in place for the performance of brain imaging in this longitudinal, repeated measures study, and the successful piloting of several brain-activation paradigms to measure specific neural systems (e.g., the reward system) across puberty in children. Nonetheless, in the past few months, we have screened several children who were excluded from this study because they did not display a normal tempo of growth as determined by skeletal age within one year of chronologic age. Thus, these participants showed evidence of early gonadal activity, and possibly, a subclinical form of precocious puberty that was not consistent with their chronologic age or their Tanner Stage. We wish to investigate the effects of these early changes in gonadal activity on brain structure and function. Most studies of puberty do not include bone age in their selection criteria and findings of alterations in brain function accompanying elevated bone age relative to chronologic age will be an important methodologic consideration to guide future studies of puberty.